Stall problem on 1970 280SE

Try the control valve / heat sensor unit mounted on the injection pump. It's the device with the water hoses attatched to it and controls the mixture throughout the temperature range of the engine.

Russ

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Air / fuel mixture is probably too lean. Upon cold start, the cold start system carries the engine but as the engine warms up this "help" phases out and the normal idle setting comes into play. That's what's too lean.

One possibility of the engine running too lean is a vacuum leak that allows unmetered air to enter the intake manifold and dilute the air / fuel mixture to the point of stalling.

The sputtering on acceleration, even when cold, speaks again of too lean a air / fuel mixture.

A gas engine needs about a 14:1 air fuel ratio to run at a constant speed, acceleration cuts this to about 12:1 and deceleration raises it to about 16:1.

IMHO your 280SE is trying to run on a 16:1 ratio all the time, that's the basic problem. You need to find out why.

I have seen a bad coil do this. Examine the spark, if weak yellow, replace coil.

-Kent